Was there a chance that the Nazis could've won the war when the US steps in?

by tjeco

Or were they fighting a losing war soon as US steps in?

And what was the plan if he would have won?

rijoja

If you mean when they stepped in in Europe with land forces, no not a chance. The English and US got scared that the Soviets would conquer the whole of Europe. The English actually had a plan to attack via the baltic sea in order to stop the Soviet forces from reaching France.